1. Field of the Invention
This invention relates to a valve actuator and particularly to an improved actuator for preventing unauthorized operation of a fire hydrant.
The device of this invention especially concerns a tamper resistant valve operating nut and companion wrench.
2. Description of the Prior Art
The conversion of water resources has become an ever increasing problem especially during periods of short rainfall and in summer months. Aside from maintaining sufficient water supplies necessary and essential for industrial and personal consumption, fire protection in most municipalities is almost exclusively dependent upon the ability to meet required water demands. Most commonly, this is accomplished through a water distribution network which feeds fire hydrants with required demand flow over and above maximum normal consumption. Although the hydraulic design of these systems usually takes into consideration fluctuations in pressure or head loss, these systems cannot adequately compensate for excessive use of fire hydrants for nonauthorized purposes and the wanton and wasteful water consumption resulting therefrom. This operation of fire hydrants for mischievous or personal purposes presents a serious and frequent problem to many water and fire departments.
A typical double nozzle hydrant such as manufactured by Smith Manufacturing Co. utilizes a valve operating stem which extends through a standpipe and is accessible by an operating nut or yoke stem nut projecting above a bonnet. The operating nut conventionally is in a pentagon shape. In addition, the standard double nozzle hydrant has a nozzle and a steamer nozzle in the standpipe, each of which is sealed with a cap having the same dimensional pentagon shaped nut for operation. This structural arrangement facilitates opening and closing by fire department or other authorized personnel and allows use of a uniform size wrench. Unfortunately, the pentagon nut can also be operated by other tools such as by common pipe wrenches, pliers, hammer and chisel and other grasping tools or clamping apparatus.
Several devices were developed in an attempt to deter unauthorized hydrant usage. Some of those devices were directed at preventing removal of the nozzle outlet caps. One such device was a harness comprised of two arcuate bands of steel which had an opening at the respective ends adapted for engaging each of two discharge outlet cap nuts. The arms were bolted together at their opposite ends. That device, however, proved unsuccessful since the bolt connection could be readily severed and thus did not provide an effective deterrent.
Another fire hydrant discharge cap had two engaging surfaces for coacting with a special tool for unthreading the cap as was shown in U.S. Pat. No. 3,929,152. That device could similarly be defeated, as by wedging a sharp instrument between the interface of the cap and nozzle, which could thus loosen the threaded connection.
Another approach was directed to the encasement or covering of the pentagon shaped operating nut such as shown in U.S. Pat. Nos. 3,935,877 and 4,033,372. The devices shown in those last mentioned patents required the installation of rather cumbersome, expensive and elaborate apparatus. A major disadvantage of those devices was that they were subject to jamming and their reliability was questionable, especially under emergency use or for firefighting situations. Furthermore, the rather large diameter dome shown in the last mentioned patent provided a gripping surface for a strap which could be wrapped around the dome for frictional engagement and the valve could thus be operated. The locking system shown in the earlier patent could likewise be compromised with conventional tools.
The concept of developing a nut with a nongripping surface was also utilized in other applications such as shown by the cone shaped nut cover in U.S. Pat. No. 3,222,976, however the exposed Allen-head screws provided a method for readily removing this cone shaped cover. Another arrangement for a theft resistant nut apparatus was shown in U.S. Pat. No. 3,930,428, however the index facet arrangement has distinct shortcomings and that device was not resistant to conventional wrenches or other clamping tools.
It should also be noted that with regard to the application of the special operating wrench of this invention, U.S. Pat. No. 2,442,920 disclosed a tool for the removal of watch cases. The wrench of this invention, however, improves upon that concept for heavy duty operation and further utilizes two fixed position set screws or studs and a variably adjustable stud having a knurled handle. Furthermore, the central opening in the present invention is tapered in conformity with the conical surface of the operating nut and is also designed to provide marginal clearance space for locating the stud receiving recesses.
Another advantage of the instant invention is that it utilizes an operating nut fabricated of case hardened steel having a smooth concial surface providing an optimum angular orientation so as to prevent conventional wrenches or other tools from gripping and turning the nut. It should thus be evident that this device achieves a relatively foolproof locking system which is substantially nonjamming and relatively easy to operate.
A further advantage of this invention over the prior art is that the improved operating nut is completely compatible for use with standard hydrant assemblies and can be substituted for the corresponding pentagon stem nut.
In view of the foregoing, it should be apparent that the present invention overcomes many of the shortcomings of the prior art devices and provides an improved tamper resistant valve actuator for a fire hydrant which eliminates many of the problems of the prior art.